IP Multimedia Subsystem(IMS) and Its Applications - KNOM · Nable Communications, Inc. 3 IMS Overview • IP Multimedia Subsystem (IMS) – An architectural framework for delivering

1Nable Communications, Inc.

IP Multimedia Subsystem(IMS) and Its Applications

2007. 4. 262007. 4. 26

JunJun--Won LeeWon LeeNableNable Communications, Inc.Communications, Inc.

KNOM Conference April 26 ~ 27 2007KNOM Conference April 26 ~ 27 2007


Contents

ContentsContents

IMS OverviewIMS Overview

IMS ArchitectureIMS Architecture

IMS ApplicationsIMS Applications

IMS Enablers & ClientsIMS Enablers & Clients


IMS Overview

• IP Multimedia Subsystem (IMS) – An architectural framework for delivering IP multimedia services to

end users, originally designed by 3GPP– At the heart of Next Generation Convergent Networks

Pre-IMS Communications(Service Islands)

PrePre--IMS CommunicationsIMS Communications(Service Islands)(Service Islands)

IMS Communications(Integrated Services)

IMS CommunicationsIMS Communications(Integrated Services)(Integrated Services)


IMS Overview – Network Convergence

IMSIMS

FIXEDFIXED MOBILEMOBILE

Serv

ices

Core

AccessCon

nect

ivity

Use

r

HSSHSS

Services Location/Auth

WCDMAGERANWiMAX WLANxDSL


IMS Overview - What IMS Provides

• Services and Control– Adds call session control to the packet network – Enables peer-to-peer real-time services - such as voice, video -

over a packet-switched domain

• Mixed Multimedia– Ability to pick and mix various multimedia flows in single or multiple

sessions– Can handle real-time voice, video, data

• Connectivity Independence– Provides access to IP based services independent of the

connectivity network: mobile (3GPP’s UMTS, 3GPP2’s CDMA2000) and fixed networks (TISPAN’s NGN)


IMS Overview - Standards

• 3GPP has developed IMS for delivering “Internet Services” over GPRS• 3GPP2 is defining requirements for support of CDMA2000• TISPAN is defining the NGN network based on 3GPP IMS and

adapting 3GPP IMS to fixed access networks• OMA is defining services based on the 3GPP IMS service platform• IETF standards such as SIP is fully utilized for IMS to ease the

integration with the Internet

3GPP : 33GPP : 3rdrd Generation Partnership ProjectGeneration Partnership ProjectTISPAN : Telecom & Internet converged Services & Protocols for ATISPAN : Telecom & Internet converged Services & Protocols for Advanced Networkdvanced NetworkOMA : Open Mobile AllianceOMA : Open Mobile Alliance


IMS Overview – SIP centerred


Contents

ContentsContents






IMS Architecture - Overall


IMS Architecture - Simplified


IMS Architecture – Major Components

• HSS (Home Subscriber Server)– UPSF (User Profile Server Function)– Master user database

• Subscription-related information (user profiles)

– Performs authentication and authorization – Provides information about the physical location of user

• SLF (Subscriber Location Function)– Map user addresses when multiple HSSs are used



– User Identities• IMSI (International Mobile Subscriber Identity) : a unique user identity that is

stored in the SIM• TMSI (Temporary Mobile Subscriber Identity) : To improve privacy, a TMSI is

generated per geographical location. IMSI/TMSI are used for user identification. • IMEI (International Mobile Equipment Identity) : a unique device identity • MSISDN (Mobile Subscriber ISDN Number) : telephone number of a user

– Additional Identities with IMS• IMPI (IP Multimedia Private Identity) : a tel-uri or sip-uri. Unique to the phone.

More than one IMPU per IMPI• IMPU (IP Multimedia Public Identity) : a tel-uri or sip-uri. IMPU can be shared

with another phone. Both the phone can be reached with the same identity

NoteNoteNote



• P-CSCF (Proxy Call Session Control Function)– First point of contact for the IMS client– Assigned to an IMS terminal during registration, and does not change for

the duration of the registration – Sits on the path of all signalling messages, and can inspect every message – Authenticates the user and establishes an IPsec security association with

the IMS terminal. This prevents spoofing attacks and replay attacks and protects the privacy of the user. Other nodes trust the P-CSCF, and do not have to authenticate the user again.

– Compress and decompress SIP messages using SigComp, which reduces the round-trip over slow radio links

– May include a PDF (Policy Decision Function), which authorizes media plane resources e.g. quality of service (QoS) over the media plane. It's used for policy control, bandwidth management, etc ... The PDF can also be a separate function.

– Generates charging records



• S-CSCF (Serving CSCF)– Central node of the signaling plane– Uses DIAMETER to talk with HSS to download and upload user

profiles. No local storage for the user– Handles SIP registration thus binding the user location(IP addr) and

the SIP address– Decides to which application servers the SIP message will be

forwarded– Routing service using ENUM lookups– Multiple S-CSCF for load distribution and high availability reasons



• I-CSCF (Interrogating CSCF)– At the edge of an administrative domain– A forwarding point for SIP packets to other domain– THIG (topology hiding inter-network gateway) function

• From Rel7, this function is transferred to a new entity, IBCF(InterconnectionBorder Control Function)



• Application Servers– Host and execute services– Interfaces with the S-CSCF (ISC interface)– Example services

• Caller ID, Call waiting, Call forwarding, Call transfer, Call hold, Call pickup• Conference call• Voice mail, Unified Messaging• Text-to-speech, Speech-to-text• Push-to-talk (PTT)• Location based services• Presence, Instant Messaging• Voice Call Continuity (VCC)• Etc.

– Types• SIP AS : native IMS application server• OSA-SCS(Open Service Access – Service Capability Server) : interface with OSA

application servers using Parlay• IM-SSF(IP Multimedia Service Switching Function) : interface with CAMEL application

servers using CAP



• MRF (Media Resource Function)– Used for

• Playing of announcement (audio/video)• Multimedia conferencing • Text-to-speech and speech recognition• Real-time transcoding of multimedia data

– MRFC (Media Resource Function Controller)• Signaling plane node• Controls MRFP with a H.248 interface

– MRFP (Media Resource Function Processor)• Media plane node



• BGCF (Breakout Gateway Control Function)– Routing functionality based on telephone numbers

• SGW (Signaling Gateway)– Transforms lower layer protocols (SCTP into MTP)– Pass ISUP from MGCF to the CS network

• MGCF (Media Gateway Controller Function)– Protocol conversion between SIP and ISUP– Interfaces with SGW over SCTP– Controls resources in an MGW with a H.248

• MGW (Media Gateway)– Converting between RTP and PCM– Transcoding


IMS Architecture – REGISTER Flows


IMS Architecture – Session Setup Flows (1)





RTP


Contents

ContentsContents






IMS Applications - PoC

• PoC (Push-to-Talk over Cellular)– a walkie-talkie type service that

provided over a cellular phone network

– half duplex communications —while one person speaks, the other(s) listen

– Immediate and instant communication

– Video and text as well as voice– Open standard-based (OMA)


IMS Applications - Video Sharing

• Video Sharing– Sharing one-way live video or

video clips in real time during a normal voice call

– Enhances a voice call with the ability to share video among users

• New opportunity for mobile operators to gain additional revenue from voice calls

• Prolonged voice call duration

– Open standard based (GSMA)


IMS Applications – Video Sharing

(From Nokia(From Nokia’’s WP)s WP)


IMS Applications – VCC (Voice Call Continuity)

Wi-FiAccess

IP CoreNetwork

IMS Core

VCC AS

MSC

MGWMGCF

CDMA 1x

Handover

Dual-BandHandset Device

OEP(other end point)

OEPWiBro

1x

Anchoring and Switching at VCC AS1) Basic Concept of VCC1) Basic Concept of VCC


IMS Applications – VCC (Voice Call Continuity)

PS

CS

[2]

[4’]

[3]

[7][5]

• Call Flows

[1] Call Origination

[2] ISUP:IAM

[3] SIP:INVITE

[4] SIP:200 OK

[5] ISUP:ANM

[6] 1x TCH Setup

[7] SIP:ACK

[8] SIP:BYE

[9] SIP:200 OK

[3’]

UE

{ckt} {pkt}

[1]

MGCF + MGW

[9][8]

IMS Core + VCC AS

[4] [7’]

OTHER END POINT

[6]

MSC/VLR

2) Signal Flow for 2) Signal Flow for VoIPVoIP to CDMA Handto CDMA Hand--Over Over


Contents

ContentsContents






Overall IMS Architecture

WiBro

WiFi

IMS ClientsIMS Clients

xDSL

CDMA

MRF

MGCF

IMS Enablers (or Application Servers)IMS Enablers (or Application Servers)

IMS CoreIMS Core

HSDPA

IMIMPresencePresence VCCVCC PoCPoC

MRFCMRFC SS--CSCFCSCF

II--CSCFCSCF

PP--CSCFCSCF

BGCFBGCF

MGCMGC SGWSGW

MGWMGW

MRFPMRFP

HSSHSS

SLFSLF

Video ShareVideo SharePortable toPortable toAny DeviceAny Device

PSTN/PLMNManaged IP NetworkManaged IP Network


OMA Perspectives

Voice

MessagingSMS,MMS

IMPush2X(show/video)

PersonalizedContents

LBSTelematics

PIMS

Broadcast, Music

M-game

Avatar, Ringtone

M-bankingTrading

PaymentPurchasing

Communication

Information

Entertainment

Finance

• Trend of Mobile Phone: Convergence of Data Service

Four Categories of Data Service,

>> Communication, Entertainment, Information, and Finance


OMA Enabler Roadmap


OMA Reference Model

Aggregation Proxy

SIP

/ IP

Cor

e

XDM

Clie

nt

ResourceList Server

PresenceServer

PresenceXDMS

Shar

ed X

DM

S

XDM-3

XDM-1

PRS-5

PRS-6

PRS-7

PRS-8

PRS-10

PRS-9 PRS-4

PRS-3

RLSXDMS

PRS-11

PRS-12

PresenceSource

PRS-1

PRS-2

Watcher

Rem

ote

Pres

ence

Net

wor

k (b

ased

on

SIP/

IP C

ore)

IP-1

DMCDMS

DM-1

XDM-2

XDM-4

Content Server

PRS-13

PRS-14

PRS-15


IMS Client Overview

Application Part

IMS Client IMS Client

FrameworkFramework

Device Specific Part

IMS Client IMS Client can be layered into 3 main parts among which IMSCF(IMS Client Framework) is the mostimportant part to be an IMS-compliant client.

SW AV Codec

PTA (Push-to-All)

IMS enabled Game

Active Phone book VoIP

Video Conference

Instant Messenger

GSMA Video Sharing OMA PoC

Media Processing

RTP/RTCPSIP/SIMPLE

XCAP

MSRP

SigComp

SDP

DSP Chip

Windows Mobile 5.0

Qualcomm REX/DMSS

WIPI

Symbian

BREW

Digest AKA


IMS Client Overview

• Technologies– Various Protocols Support

• SIP/SDP/RTP/RTCP/MSRP/XML/XCAP/…

– Various Standard Organizations• 3GPP, OMA, IETF,…

– Various Media Support• Voice, Video, Music, Images, etc.

• Wide range of Platform Support (Portability)– Any device– Key requirement for IMS client platform

• End-user applications– Attractive and Intuitive GUI– Easy to use


IMS Client Framework

Memory, Network, File I/O, EventA/V Codec, Device

WiBro/Wi-Fi

SPIRIT,GIPS,Etc.

Platform Adaptation Layer

RTP/RTCP

SIP/SIMPLEw/ sigcomp MSRP XCAP

Media API IMS Core APITAPI etc.

CDMA/GSM

VideoSharing

VoIP/Conf

IM/Presence PoC

GenericSession

Mgt.

GenericEventMgt.

Other APIs

3rd

PtyEnablers

OtherDevices &Features

High Level APIs for IMS Applications

VCCClient

IMS Core Adaptation for Windows Window Mgt Local Data Mgt

Any Device and Platform (Qualcomm REX/DMSS, Windows Mobile, Symbian, etc.)

Video Telephony

InstantMessenger

InstantMessenger

VCC

VideoSharing

Application

3rd PtyAppls

3rd PtyAppls

IMS Framework

Windows OSAdaptation

(Option)

Applications

Platform & APIs

Nable IMS Client Architecture

3rd

PtyEnablers

MediaFilter

37Nable Communications, Inc. Contact : JunContact : Jun--Won Lee, Won Lee, [email protected]@nablecomm.com, +82, +82--1010--68246824--88258825

IP Multimedia Subsystem(IMS) and Its Applications - KNOM · Nable Communications, Inc. 3 IMS Overview • IP Multimedia Subsystem (IMS) – An architectural framework for delivering

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